Dozens of people are feared dead and around 100 injured on Thursday after an explosion and a fire at a bar in the Crans-Montana ski resort in Valais Canton, southwestern Switzerland, local police said.

The fire broke out at 1:30 a.m. local time in a bar called Le Constellation, police said in a statement.

More than 100 people were inside the bar at the time of the explosion, according to reports.

Those injured in the blast and subsequent fire suffered serious injuries and were taken to hospitals in Sion, the capital of Valais Canton, and other cities, Valais Canton Police Chief Frederic Gisler said at a press conference.

Swiss authorities don't know exactly how many people are dead and injured because there wasn't a guest list for the event at the bar, according to a reporter from the Swiss newspaper Blick.

Swiss authorities confirmed the incident is being treated as a fire and not an attack.

Helicopters and ambulances, including some from abroad, rushed to the scene, as the intensive care units and operating rooms of local hospitals are at full capacity, said local officials at the press conference.

Emergency responders remain on the scene as the investigation into the cause of the explosion continues.

President of the Swiss Confederation Guy Parmelin postponed his planned New Year's address and expressed condolences to the families of the victims.

The Valais cantonal administration announced that the canton has entered an emergency.

(With input from agencies)